Xing Jiabao, Tang Yue, Li Jiaxin, Wu Changwei, Gu Yiru, Li Xiaobo, Zhang Hu, Zhang Mingwen, Wang Xiao, Zhou Xing, Gan Xuetao, Wu Di, Zeng Jinghui, Zhai Tianyou, Xu Hua
Key Laboratory of Applied Surface and Colloid Chemistry of Ministry of Education, Shaanxi Key Laboratory for Advanced Energy Devices, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710119, P. R. China.
Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, 518055, P. R. China.
Adv Mater. 2024 Dec;36(50):e2407655. doi: 10.1002/adma.202407655. Epub 2024 Aug 6.
2D ferroelectric materials have attracted extensive research interest due to potential applications in nonvolatile memory, nanoelectronics and optoelectronics. However, the available 2D ferroelectric materials are scarce and most of them are limited by the uncontrollable preparation. Herein, a novel 2D ferroelectric material AgCrS is reported that are controllably synthesized in large-scale via salt-assist chemical vapor deposition growth. By tuning the growth temperature from 800 to 900 °C, the thickness of AgCrS nanosheets can be precisely modulated from 2.1 to 40 nm. Structural and nonlinear optical characterizations demonstrate that AgCrS nanosheet crystallizes in a non-centrosymmetric structure with high crystallinity and remarkable air stability. As a result, AgCrS of various thicknesses display robust ferroelectric polarization in both in-plane (IP) and out-of-plane (OOP) directions with strong intercorrelation and high ferroelectric phase transition temperature (682 K). Theoretical calculations suggest that the ferroelectricity in AgCrS originates from the displacement of Ag atoms in AgS tetrahedrons, which changes the dipole moment alignment. Moreover, ferroelectric switching is demonstrated in both lateral and vertical AgCrS devices, which exhibit exotic nonvolatile memory behavior with distinct high and low resistance states. This study expands the scope of 2D ferroelectric materials and facilitates the ferroelectric-based nonvolatile memory applications.
二维铁电材料因其在非易失性存储器、纳米电子学和光电子学中的潜在应用而引起了广泛的研究兴趣。然而，现有的二维铁电材料稀缺，且大多数受到制备过程不可控的限制。在此，报道了一种新型二维铁电材料AgCrS，它通过盐辅助化学气相沉积生长法可大规模可控合成。通过将生长温度从800℃调至900℃，AgCrS纳米片的厚度可精确调控至2.1至40纳米。结构和非线性光学表征表明，AgCrS纳米片结晶为具有高结晶度和显著空气稳定性的非中心对称结构。因此，不同厚度的AgCrS在面内（IP）和面外（OOP）方向均表现出强大的铁电极化，具有强相互关联性和高铁电相变温度（682 K）。理论计算表明，AgCrS中的铁电性源于AgS四面体中Ag原子的位移，这改变了偶极矩排列。此外，在横向和垂直的AgCrS器件中均展示了铁电开关特性，其表现出具有明显高阻和低阻状态的奇异非易失性存储行为。本研究拓展了二维铁电材料的范围，并推动了基于铁电的非易失性存储器应用。
